1. Field of the Invention
The present invention relates to an iron golf club head. More specifically, the present invention relates to a solid golf club head having no hollow regions in a golf club head main body, or to a golf club head having a hollow region in a portion thereof.
2. Description of the Related Art
Conventionally, iron golf clubs use a titanium alloy (specific gravity substantially equal to 4.5), for example, in a face that impacts a golf ball, thus achieving a lighter weight face. On the other hand, however, by placing a metallic heavy member having high specific gravity in a desired location as a weight chip (adjusting member) adjusting for a center of gravity of the golf club head, the moment of inertia of a golf club head may increase, or the center of gravity of the golf club head may be lowered. The carry distance of the struck golf ball thus increases, or the flight direction characteristics of the struck golf ball improve. Further, the depth of the center of gravity of the golf club head can be changed so as to shift the center of gravity away from the impact surface. However, methods of disposing the weight chip adjusting for the center of gravity in a desired position do not go beyond adjusting methods that make minute adjustments to the center of gravity position, or adjusting methods that make minute adjustments in the moment of inertia. There are limitations on how much the position of the center of gravity such as the height or the depth of the center of gravity can be changed, and there are limitations on how much the moment of inertia can be increased.
On the other hand, when lightening the overall golf club head by using, in an impact surface, an aluminum alloy having a smaller specific gravity than that of a titanium alloy (aluminum alloy specific gravity substantially equal to 2.5), the amount that the golf club head is lightened may be allocated to the adjusting weight chip, thus increasing the degree of freedom in performing using the adjusting weight chip for the center of gravity. However, the physical strength (maximum tensile strength) of the aluminum alloy is low when 7075 aluminum alloy, for example, is used. Consequently, the thickness of a member made from this alloy must be made thicker when used as a face member that forms the impact surface. Accordingly, the advantages of low specific gravity aluminum alloys cannot be utilized effectively due to the amount that the thickness of the face member increases, and there is a limit in how much the center of gravity position and the moment of inertia of the golf club head can be changed.
JP 2002-35182 A and JP 2002-65912 A disclose an iron golf club head whose impact surface (face) that impacts a golf ball is configured by using a member made from an aluminum alloy in which fine, hard particles or silicon carbide are or is dispersed. However, the member used here increases the spin of the golf ball, and the physical strength of the aluminum alloy is similar to that of conventional aluminum alloys. Consequently, the face member must be made thicker, and the center of gravity position and the moment of inertia continue to be similar to their conventional values. The carry distance and the flight direction characteristics of a struck golf ball thus cannot be improved compared to their conventional results by using the weight chip adjusting for the center of gravity of the golf club head.